Fix execution context setting for iframes

common/frame.go

@@ -447,10 +447,31 @@ func (f *Frame) setContext(world executionWorld, execCtx frameExecutionContext)
 		panic(err)
 	}
 
+	// There is a race condition when it comes to attaching iframes and the
+	// execution context that apply to these frames. What usually occurs is:
+	//
+	// 1. An exec context for about:blank is first set;
+	// 2. A new set event is received for exec context for the url pointing
+	//    to the actual destination for the iframe;
+	// 3. Finally the execution context for about:blank is destroyed, not
+	//    for the second execution context.
+	//
+	// This is the order of events when iframes are in use on a site, and
+	// so it is safe to nil the original execution context and overwrite it
+	// with the second one.
+	//
+	// The exec context destroyed event will not remove the new exec context
+	// since the ids do not match.
+	//
+	// If we didn't overwrite the first execCtx with the new one, then
+	// waitForExecutionContext could end up waiting indefinitely since all
+	// execCtx were destroyed.
 	if f.executionContexts[world] != nil {
-		f.log.Debugf("Frame:setContext", "fid:%s furl:%q ectxid:%d world:%s, world exists",
+		f.log.Debugf("Frame:setContext", "fid:%s furl:%q ectxid:%d world:%s, overriding existing world",
 			f.ID(), f.URL(), execCtx.ID(), world)
-		return
+
+		f.executionContexts[world] = nil
+		f.documentHandle = nil
 	}
 
 	f.executionContexts[world] = execCtx

common/frame_session.go

@@ -663,18 +663,25 @@ func (fs *FrameSession) onExecutionContextCreated(event *cdpruntime.EventExecuti
 	if err := json.Unmarshal(auxData, &i); err != nil {
 		k6ext.Panic(fs.ctx, "unmarshaling executionContextCreated event JSON: %w", err)
 	}
-	var world executionWorld
+
 	frame, ok := fs.manager.getFrameByID(i.FrameID)
-	if ok {
-		if i.IsDefault {
-			world = mainWorld
-		} else if event.Context.Name == utilityWorldName && !frame.hasContext(utilityWorld) {
-			// In case of multiple sessions to the same target, there's a race between
-			// connections so we might end up creating multiple isolated worlds.
-			// We can use either.
-			world = utilityWorld
-		}
+	if !ok {
+		fs.logger.Debugf("FrameSession:onExecutionContextCreated:return",
+			"sid:%v tid:%v ectxid:%d missing frame",
+			fs.session.ID(), fs.targetID, event.Context.ID)
+		return
 	}
+
+	var world executionWorld
+	if i.IsDefault {
+		world = mainWorld
+	} else if event.Context.Name == utilityWorldName && !frame.hasContext(utilityWorld) {
+		// In case of multiple sessions to the same target, there's a race between
+		// connections so we might end up creating multiple isolated worlds.
+		// We can use either.
+		world = utilityWorld
+	}
+
 	if i.Type == "isolated" {
 		fs.isolatedWorlds[event.Context.Name] = true
 	}